Understanding Global Terrain Data

Flight simulation has evolved far beyond simple flat landscapes. Today, the most immersive experiences rely on accurate representations of the Earth’s surface. Global terrain data provides the raw information needed to build mountains, valleys, coastlines, and urban areas with striking fidelity. For pilots and enthusiasts, this data transforms a generic virtual sky into a lifelike environment where visual navigation, altitude awareness, and procedural training truly matter.

At its core, terrain data consists of digital elevation models (DEMs) that record elevation at every point on a grid. These models come in various resolutions: SRTM offers 30-meter or 90-meter cells, while commercial datasets like those from Airbus or Maxar can deliver submeter accuracy. Beyond elevation, advanced terrain data includes land cover classification, orthoimagery (aerial photographs corrected for distortion), and even bathymetry for coastal regions. Combining these layers creates the rich, textured world you see from the cockpit.

Understanding what data is available and how it is captured—by satellite radar, aerial lidar, or photogrammetry—is the first step to using it effectively. Each source has trade-offs in coverage, resolution, and update frequency, making it important to choose the right type for your goals. Whether you are simulating a mountain approach in the Andes or a low-altitude flight over European farmland, the quality of your terrain data directly impacts realism and training value.

Key Sources of High-Quality Terrain Data

Numerous organizations provide free and commercial global terrain datasets. The most commonly used sources for flight simulation include:

  • SRTM (Shuttle Radar Topography Mission): Flown in 2000 aboard the Space Shuttle Endeavour, SRTM acquired near-global elevation data between 60°N and 56°S. The 1-arc-second (~30 m) product is freely available through the USGS Earth Explorer and remains the baseline for many simulator add-ons. Its consistent quality and wide coverage make it ideal for large regions.
  • ASTER GDEM: Produced by NASA and Japan’s METI using stereo imagery from the ASTER instrument on Terra satellite. It offers 30-meter resolution with better vertical accuracy than SRTM in steep terrain. ASTER GDEM v3 includes significant corrections and is available at no cost via the NASA LP DAAC.
  • Copernicus DEM: The European Space Agency’s Copernicus program provides the EU-DEM (25 m) and GLO-30 (30 m) datasets. GLO-30 covers the global landmass with high accuracy and is derived from TanDEM-X satellite data. It is frequently used in recent simulator scenery because of its superior void filling and resolution.
  • USGS Earth Explorer: A portal to access a vast archive of satellite imagery, elevation data, and land cover products. Beyond SRTM, you can find National Elevation Dataset (NED) for the United States at 10 m or finer, and lidar point clouds for select areas. Earth Explorer is a practical starting point for any flight simulation project.
  • OpenTopography: Aggregates high-resolution topographic data from lidar and other sources, often at 1 m or better. While coverage is limited to areas where surveys have been conducted (primarily North America and parts of Europe), the data quality surpasses global satellite DEMs. OpenTopography provides tools for downloading and processing subsets.
  • Commercial datasets: Companies like HxGN (Hexagon), Airbus (WorldDEM), and Planet (RapidEye) offer even higher resolution data. These are used by professional simulators and high-end add-on developers, but can be cost-prohibitive for hobbyists. However, some free limited versions exist for research or noncommercial use.

When selecting a source, consider the geographic region, required resolution, and the processing resources at your disposal. For most flight sim enthusiasts, SRTM or Copernicus GLO-30 provides an excellent balance of coverage and detail.

Accessing and Downloading Terrain Data

Downloading global terrain data typically involves navigating a data portal, selecting a region of interest, and choosing a file format. Most providers offer GeoTIFF (a standard raster format with embedded geolocation) or DEM (digital elevation model) files. Here are common workflows:

Using the USGS Earth Explorer

Create a free account, then use the interactive map to draw a bounding box or select a predefined area. Under “Data Sets,” expand “Digital Elevation” and choose SRTM 1 Arc-Second Global. Click “Results” to see available tiles. Each tile covers 1×1 degree (~111×111 km). Download the GeoTIFF files for your area. For large regions, you can automate downloads using the Bulk Download License Agreement and the EarthExplorer API.

Copernicus GLO-30 Downloads

The Copernicus Space Component Data Access system (ESA’s CREODIAS) provides GLO-30 tiles. You can also access them through the Planetary Computer Microsoft platform, which offers a STAC API. For scripting, tools like elevation (Python library) or gdalwarp allow downloading multiple tiles programmatically. A popular approach in the flight sim community is to use scripts that query the Copernicus portal and combine tiles into a seamless raster.

OpenTopography allows you to search by geographic area and filter by data source (e.g., SRTM, lidar). The “Point Cloud” datasets require significant processing, while the “Raster DEM” products can be downloaded directly. For lidar-derived DEMs, you may need to unzip and mosaic using GIS software.

Always verify the file format compatibility with your simulator toolset. Most scenery generators expect GeoTIFF, IMG, or raw binary files with a corresponding header. If you plan to use the data in Microsoft Flight Simulator (MSFS), you will often process it through a tool like SDK’s Resample or a third-party elevation modifier.

Processing Data for Simulator Use

Raw terrain data rarely aligns perfectly with a flight simulator’s grid system. You will need to resample, reproject, and sometimes adjust the elevation to match the simulator’s coordinate reference system. These steps are typically performed in a GIS (Geographic Information System) like QGIS or using command-line tools from the GDAL library.

Reprojection and Resample

Most DEMs come in geographic coordinates (WGS84 lat/lon). Flight simulators often use a projected coordinate system (e.g., Mercator for MSFS, or local planar projections for X-Plane). Use QGIS to reproject the raster to the target projection. Resampling is required if the cell size of the DEM differs from the simulator’s tile grid. Bilinear or cubic convolution resampling is preferred for smooth elevations; nearest neighbor may cause stair-stepping.

Merging and Mosaicking

If your area of interest spans multiple downloaded tiles, merge them into a single raster. In QGIS, use the “Merge” tool in the Raster menu. Ensure that overlapping areas are handled consistently—some datasets have seams; using a feathering algorithm or blending can reduce artifacts. The resulting mosaic should be clipped to your exact simulation area to minimize file size.

Filling Voids and Correcting Anomalies

SRTM and other satellite DEMs often contain data voids (gaps) in water bodies, deep shadows, or steep slopes. These show up as “holes” in the landscape. Use GDAL’s gdal_fillnodata.py script or QGIS’s raster calculator to interpolate across small gaps. For larger voids, substitute data from a different source, such as filling SRTM voids with ASTER or Copernicus. Some advanced users employ bathtub modeling to flatten water surfaces and remove spikes caused by radar noise.

Generating Color-Infused Elevation Textures

For a more natural look many flight sim add-ons overlay orthoimagery (satellite or aerial photos) on the terrain. Tools like Ortho4XP (for X-Plane) automatically download and mosaic satellite images from Bing, Google, or USGS. You can also create your own ortho tiles by georeferencing images and using GDAL to warp them to the DEM. The combination of accurate elevation and real-world textures dramatically enhances immersion.

Integrating Terrain Data into Flight Simulators

The method of integration depends heavily on the simulator platform. Below are workflows for the most popular simulators.

Microsoft Flight Simulator (2020)

MSFS 2020 already uses bing satellite imagery and a global DEM. However, certain areas may have poor resolution or incorrect elevation. To modify terrain, you can create a custom “Package” using the MSFS SDK. The SDK’s “Resample” tool allows you to provide a custom DEM and image tiles. This process is documented in the official Flight Simulator World Configuration guide. After building your package, install it into the Community folder. Restart the sim and your custom terrain will replace the default for that area.

Another approach is to use third-party add-ons like FS2020 Terrain Mod or Elevation Data Mod which automate the process for certain regions. However, manual creation gives you full control over quality.

X-Plane

X-Plane is particularly friendly to custom terrain. The tool Ortho4XP is the most popular solution. It downloads elevation data from sources like USGS or viewfinderpanoramas, generates meshes, and tiles satellite imagery. You can configure the level of detail (mesh ZL), source imagery provider, and whether to use overzoom imagery. Ortho4XP outputs a folder hierarchy that you place into X-Plane’s Custom Scenery directory. The official manual and community forum are excellent resources. For ultra-high detail, combine Ortho4XP with xOrganizer to manage load order.

Ortho4XP also supports creating “water masks” and correcting seams at tile boundaries. Experienced users can generate DSF (X-Plane's scenery format) directly from processed DEMs using the MeshTool included with the Python-based X-PNG scripts.

Prepar3D and Lockheed Martin Prepar3D (P3D)

P3D uses a BGL format for terrain. The Resample tool from the P3D SDK converts DEM files (in GeoTIFF) into BGL terrain files. You must specify source data, output path, and coordinates. After compilation, place the BGL in the Scenery/World folder. Additionally, many photorealistic scenery add-ons use SbuilderX (a free tool) to create vector-based land class and elevation data for P3D. The process is more manual than X-Plane, but the results are very stable.

DCS World

DCS World uses a proprietary terrain format. Custom terrain creation is highly complex and usually left to official module developers. However, you can enhance certain areas by importing corrected elevation data via the Mission Editor’s “Terrain” tab (only works for standard maps). For terrain modification beyond that, you would need the DCS World SDK and advanced modeling skills.

Optimizing Performance and Realism

High-resolution terrain data comes at a cost: performance. Large DEMs with many vertices and full orthoimagery tiles can severely impact frame rates. Here are best practices to balance detail and smoothness:

  • Use level of detail (LOD): Most simulators handle LOD automatically, but when building custom scenery, consider generating multiple resolution tiers. For example, tile the region at 1 m/pixel near airports and 15 m/pixel for remote areas. Ortho4XP allows setting different zoom levels for the base mesh vs. overlays.
  • Limit tile size: Keep individual tiles no larger than 4096×4096 pixels. Larger textures cause memory spikes. Split large DEMs into chunks no larger than the simulator’s grid cell (e.g., 1×1 degree for X-Plane).
  • Optimize orthoimagery compression: Use lossy compression (JPEG with high quality) for orthophotos instead of PNG or TIFF. DDS (DirectDraw Surface) formats with mipmaps often perform better in MSFS and P3D. Tools like DXT5 can be applied during conversion.
  • Pre-cache elevation: Some simulators re-sample elevation data each time you load a flight. For X-Plane, the Ortho4XP patch “Convert to DSF” pre-processes the mesh to speed up loading.
  • Use water masks: Flat water bodies can be created by masking water areas in the DEM. This prevents the mesh from showing stair-stepped lakes and reduces vertex count over water.

Realism also involves accurate coastlines and airports. Check for elevation anomalies near runways—many elevation datasets have errors over airports due to radar reflections. Manually flatten the runway threshold elevation using a vector polygon in QGIS. Several community forums contain “airport elevation fixes” for major hubs.

Benefits for Flight Training and Entertainment

Accurate terrain data is not just eye candy. For pilots in training, it enables realistic visual navigation, more reliable altitude management during approaches, and better awareness of obstacles and terrain clearance. Simulating a VOR approach into Innsbruck or a challenging visual approach to Rio de Janeiro becomes a true test of skill when the mountainous terrain matches the real world. Many flight schools now use custom terrain data in their simulators to recreate local airports and unique obstacles, reducing the need for expensive airborne training hours.

For entertainment, the immersiveness boost is undeniable. Flying over your hometown with accurate buildings, hills, and rivers changes the simulation from a generic game into a personal connection. Virtual pilots who fly airliner routes over the Himalayas, the Alps, or the Grand Canyon will appreciate every ridge and valley rendered faithfully.

Moreover, using global terrain data teaches valuable skills in GIS and data processing—competencies increasingly valued in aviation careers. Understanding how to acquire, manipulate, and integrate geospatial information is directly applicable to real-world flight planning and aeronautical chart production.

Conclusion

Accessing and using global terrain data transforms a flight simulator from a flat approximation into an authentic representation of the world. By sourcing high-quality elevation and imagery from providers like USGS, Copernicus, and OpenTopography, then processing the data with GIS tools and integrating it into your simulator of choice, you can achieve levels of realism once reserved for professional training devices. Whether your goal is to enhance entertainment, improve training outcomes, or simply explore the Earth from the virtual cockpit, the effort invested in custom terrain data pays back richly in immersion and accuracy.

Start small—choose a familiar region, download a few SRTM tiles, and use Ortho4XP or the MSFS SDK to replace the default terrain. As you become comfortable with the workflows, expand to larger areas and higher-resolution sources. The community resources available online are extensive, with active forums where you can seek guidance and share your results. Every flight you take over custom terrain will remind you why this hobby continues to captivate.